Endoscopic tissue manipulators, such as grasping and extracting forceps, are well known. One of the challenges of designing these instruments is to securely hold the tissue while avoiding damage to the tissue. Some of the difficulties encountered when working endoscopically are that the work space is considerably smaller than with more traditional open surgical procedures. As a result, grasping tissue can be more difficult to accomplish.
Additionally, because of the nature of the working space, once tissue is damaged due to grasping, the damage may be more difficult to detect and correct. The operator often finds it harder to visualize and to manipulate tissue when working endoscopically.
Moreover, when tissue is grasped through an endoscopic device, the grasp can be very tenuous and involve a very small amount of tissue. The operator may need to make do with this situation as he may not be able to get a better grasp of the tissue or a better field of visualization. Even in traditional open surgical procedures, this problem of grasping tissue without causing damage persists.
For example, in many vascular procedures, the grasping device or forceps is modified to attempt to minimize damage to fragile blood vessels. One way of accomplishing this is to use "shod" clamps. This refers to the practice of placing a material, usually a short length of tubular fabric or elastomer, on the grasping portions of the clamp. This solution is not completely satisfactory because the tubular material tends to slip off the clamps. Additionally, with shod devices, the tubular material may prevent a sufficient grasp of the tissue. In summary, there are competing requirements in designing a device to grasp tissue. That is, the device must grasp the tissue sufficiently for whatever further manipulation is required as well as avoid damage to the tissue as much as is feasible.
Another challenge for physicians during endoscopic procedures involves suturing tissue, typically to close an incision. Conventional sutures require each individual stitch to be tied separately, a tedious task under even the best of conditions. Certain specialty suture techniques do not always require tying of each individual stitch, but they may have other considerations which render the technique difficult or time-consuming.
For example, a purse-string suture may be placed by pushing a needle carrying suture material through successive folds of tissue. This is typically done in an annular pattern and the suture is tightened by pulling the two ends. Thus, the tissue is drawn together in a fashion reminiscent of a purse string. The two ends of the suture may be secured, typically by tying them together or perhaps knotting off an end. The purse string technique is fairly time-consuming because each individual fold of tissue must be arranged by the surgeon and then the needle is pushed through. Also, it is tedious to arrange the folds symmetrically and evenly. The problems are amplified when the surgery is carried out in a small space or with a small field of visualization, such as with endoscopic techniques.